The proposed research involves a study of lens regeneration from the iris of neural retina regeneration from the pigmented, retinal eipthelium in urodele amphibians. It is hoped to obtain information concerning the stimuli which release these metaplasias and the role of trophic factors during regeneration. Synthesis of macromolecules and cytological changes in the reacting tissues will also be studied. Some of the aspects to be investigated are the ultrastructural and synthetic events taking place in lens capsule formation during lens regeneration in adult newts and possible ultrastructural changes in the neural retina during lens regeneration which might correlate with the changes in RNA and protein synthesis recently identified in the neural retina. Studies on the role of nerve growth factor and spinal ganglia in stimulating lens regeneration in organ culture of irido-corneal complexes will be continued and compared with the action of retinal extracts. Studies on neural retinal regeneration from the pigmented retina of newt and salamander larvae under several conditions of isolation in the eye and in fin mesenchyme will also be continued. Isolation of crystallins from normal and regenerating lenses with SDS-urea polyacrylamide gel electrophoresis will be attempted.